Gagnebina Neck. ex DC., Prodr. [A.P. de Candolle] 2: 431. 1825.
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https://dx.doi.org/10.3897/phytokeys.240.101716 |
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https://treatment.plazi.org/id/4110BCB3-1691-9643-897E-F3C56D48CB17 |
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scientific name |
Gagnebina Neck. ex DC., Prodr. [A.P. de Candolle] 2: 431. 1825. |
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Gagnebina Neck. ex DC., Prodr. [A.P. de Candolle] 2: 431. 1825. View in CoL
Figs 144 View Figure 144 , 145 View Figure 145 , 146 View Figure 146 , 159 View Figure 159
Type.
Gagnebina tamarascina (Lam.) DC. [≡ Mimosa tamariscina Lam. (= Gagnebina pterocarpa (Lam.) Baill.)]
Description.
Unarmed shrubs or small trees, branched from the base, 1-6 (10) m (Fig. 144M View Figure 144 ); brachyblasts absent, perulate resting buds present, the scales striate with raised nerves. Stipules dimorphic, those on leaves formed just after the resting bud breaks striate, stramineous, similar in colour and texture to the resting bud scales, caducous, becoming subulate or setose distally on shoots, the stipule type most commonly seen on flowering and fruiting branches. Leaves bipinnate, nectaries present between the lower pair of pinnae or mid-petiole, sometimes between additional pinnae; pinnae (3) 5-40 pairs per leaf, opposite or sub-opposite, leaflets numerous, linear to oblong with truncate bases, pinnately veined, usually glabrous or ciliate. Inflorescence usually a condensed spike (a true spike in one species, Fig. 145J View Figure 145 ), pedunculate, the peduncle often bearing a few lanceolate bracts, 1-8 in the leaf axils, the leaves sometimes suppressed and forming a paniculiform secondary inflorescence, this immersed in (or rarely exserted above) the foliage, calyx often constricted into a pseudopedicel and inflorescence appearing racemose; bracteoles subtending each flower carinate, 1-nerved; inflorescences composed of sterile flowers proximally, fertile flowers distally, and often a few functionally staminate flowers in between. Flowers with sepals and petals valvate in bud; sterile flowers with a 5-lobed calyx, fused ½-¾ its length, lobes with a central raised nerve; petals 5, free or connate, 1-nerved, staminodia 10, showy, filamentous or flattened and ribbon-like, white or rarely rose-coloured; functionally staminate flowers similar to the fertile ones but either lacking or having only a rudimentary ovary; hermaphrodite flowers similar to the sterile ones but larger, with a 5-lobed calyx and 5 free (rarely connate), usually linear or lanceolate, 1-nerved petals; stamens 10, ovate to linear, either with a terminal apiculum or lacking a gland, sagittate at the base; pollen of acalymmate 8-grained porate polyads, exine verrucate; ovary ovate, stipitate or sessile, densely strigose apically with silky white hairs, stigma punctate. Fruits either sessile or stipitate, compressed, either elastically dehiscent from the apex and recurved but not coiled after dehiscence, or indehiscent or tardily inertly dehiscent; pericarp woody in elastically dehiscent species, coriaceous to chartaceous in the indehiscent ones, the sutural ribs often greatly thickened or modified into flattened wings (Fig. 146K View Figure 146 ), the interior of the fruit usually invaginated between the seeds. Seeds obliquely or laterally positioned, ovate to rhomboidal, with the pleurogram either U-shaped or forming nearly a complete oval on the face of the seed.
Chromosome number.
2 n = 26 ( Goldblatt 1981b).
Included species and geographic distribution.
Seven species. Madagascar, Mauritius, the Mascarenes and Comoros Islands, Aldabra (Fig. 159 View Figure 159 ).
Ecology.
Usually along rivers in evergreen or deciduous woodlands; one species [ G. commersoniana (Baill.) R. Vig.] weedy and found in a wide array of habitats. The winged pods of G. pterocarpa have allowed it to colonise islands in the Indian Ocean; G. commersonia also has lightweight pods and in addition to being a widespread weed in Madagascar, it is found on Aldabra.
Etymology.
Named in honour of Françoise Gagnepain, French botanist (1866-1952).
Human uses.
Wood used locally for building houses, reportedly used in making Maintirano paper (Bosch et al. 2011).
Notes.
Closely related to Dichrostachys and Alantsilodendron (Fig. 143 View Figure 143 ) and differing from these genera in having resting buds with perulate scales instead of brachyblasts, as well as having dimorphic stipules.
Taxonomic references.
Lewis and Guinet (1986); Luckow (1995); Luckow and DuPuy (2000), all with illustrations.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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